The French Environment Ministry just announced a new law that will require all non-residential buildings to switch off[3] interior and window display lighting at night. The law, which will come into effect on July 1st, is expected to not only radically reduce light pollution[4], but also save an amount of energy each year that is roughly equivalent to the annual energy consumption of 750,000 households.

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The new energy efficiency law[6] will require shops and offices throughout France to turn off their lights one hour after the last worker leaves the building. Starting July 1 all shop window displays will be turned off at 1 a.m. Shop windows may only be lit from 7 a.m. or an hour before opening time, while necessary public lighting will not be lit before sunset. Exceptions will be made during Christmas and other significant events, as well as in some tourist and cultural areas.

According to the ministry, the new law is expected to save about two terawatt/hours of electricity a year—the equivalent of the annual consumption of 750,000 households. It will prevent the release of about 250,000 tons of carbon dioxide[7] into the atmosphere. The French ecology minister, Delphine Batho, expressed her hopes that the decree regulating the operation of lighting non-residential buildings will change the public’s attitude towards energy-saving practices and make France a pioneer in preventing light pollution.